Studies at Odds Over Soil Carbon
A new study, the results of which have been released as part of the ongoing analysis of data collected as part of the 2007 Countryside Survey, is at odds with a previous accepted analysis of carbon released from soil in England and Wales.
In 2005, Nature published the results of a study led by Prof. Guy Kirk of Cranfield University, based on the National Soil Inventory, a series of measures taken between 1978 – 83 and 1994 – 2003. Prof. Kirk and colleagues estimated that from 1978- 2003 there had been an estimated loss of 4m tonnes of carbon a year from the soils of England and Wales. Because of Scotland’s peaty soils, the team estimated that the total loss of carbon from the whole of the UK over this period was approximately 13m tonnes. As the loss had occurred across all land types the team suggested that the losses were linked to climate change.
Now a team led by Professor Bridget Emmett at CEH Bangor has compared Countryside Survey data collected between 1978 and 2007. The ecologists found that the carbon concentration in the top 15cm of the soil increased between 1978 – 1998 and then decreased from 1998 – 2007, leading to no net change in soil carbon concentrations. In arable land there was a net loss of carbon, probably due to soil disturbance through ploughing.
Speaking to the Observer, where the story was reported yesterday, Prof. Emmett said that “the amount of carbon in topsoils across England and Wales is about 2bn tonnes so detecting a change of even 4m tonnes per year is very challenging. Small differences in methods between the two surveys can therefore have a large effect”. Scientists have proposed that a study group with an independent statistical expert should be convened to examine why the two studies may differ.
Rise in UK carbon emissions disputed by report: Observer, Sunday 7th March, Juliette Jowit.
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